THREE OF Britain's top five quarrying companies are this morning publicly renouncing their rights to extract stone from nine sensitive sites in the National Parks.

ARC, Aggregates Industries and Tarmac are together giving up well over 30 million tons of mineral reserves which, they say, will not now be taken out of two quarries in Snowdonia, four in the Peak District and three in the Yorkshire Dales.

Their move follows a promise last week by the quarrying industry to put its operations in National Parks on a more environmentally friendly basis - recognising that this was its Achilles' heel in terms of public acceptability.

Environmentalists greeted the move with a mixture of astonishment, wariness and delight. "It's a really positive initiative that they've embarked upon, and very encouraging, said Ruth Chambers, minerals campaigner for the Council for National Parks pressure group.

"It will save a lot of park landscapes from damaging development." The council's director, Vicki Elcoate said: "This is a landmark decision for the National Parks."

The three big firms are each pledging that they will not re-open currently dormant quarries where they have planning permission to do so, and in two cases, not seek an extension to permissions that are coming to an end.

One of the sites in particular, Ribblehead in the Yorkshire Dales, has the potential to cause enormous damage if it were worked. Lightly quarried in the past, it sits in the "three peaks" of Ingleborough, Whernside and Pen-y-Ghent. Working the full permission currently held by ARC, Britain's second largest quarrying company, would leave an enormous gash on Ingleborough's north-eastern slope, visible for many miles, besides destroying much of the stunning limestone pavement - the landscape feature associated with the area.

Ribblehead, along with two other sites, will never be quarried again," said Simon Vivian, ARC's chief executive, and chairman of the Quarry Products Association, the industry's umbrella body.

"If prohibition notices are served by the respective National Park authorities, we will not contest them. This will effectively rescind our planning rights without compensation." Planning authorities have rarely used prohibition orders in the past for fear of long and expensive legal battles.

ARC says it is giving up its right to take 23 million tons of limestone from Ribblehead, as well as smaller amounts of rock from nearby Helwith Bridge and from Arenig quarry near Bala in Snowdonia. Tarmac, Britain's largest producer of aggregates (sand, gravel and crushed rock), is announcing that it will not contest prohibition orders at three dormant National Park quarries: Hartington and Furness, in the Peak District, and Pengwern in Snowdonia.

Aggregate Industries, the fifth biggest company, is announcing that it will not revive the dormant Hartshead quarry in the Peak District and not apply to extend the life of either Isle of Skye quarry, also in the Peak, and Cool Scar quarry in the Yorkshire Dales, both of whose planning permissions are set to expire within four years. The company has also gone further and says: "Within existing boundaries of the national parks, the company will no longer submit applications under any circumstances for new green-field mineral workings, or submit applications for the lateral extension of any existing quarry outside the currently consented boundaries of the site." "We recognise the particular sensitivity of quarrying in the National Parks," said David Tidmarsh, Aggregate Industries' managing director.

"That is why we have effectively announced today the beginning of the end of our activities [there]."

The companies' decisions follow a National Parks initiative announced last week by the Quarry Products Association during Minerals 98, the industry's Publicity Week, which had been denounced by Friends of the Earth as a "public relations exercise for an unsustainable dinosaur industry".

The association said the industry would work with Government and the National Parks authorities to let planning permissions be removed from dormant quarries, clarify those which are uncertain, and not apply for new permissions except in particular circumstances.

The idea was largely pushed through by John Mortimer, an executive of ARC, and the Minerals 98 chairman, who had realised that for all the restoration work minerals companies now carry out, quarrying in cherished and highly protected landscapes such as the National Parks is always likely to be treated with hostility by the public. The Peak District and the Yorkshire Dales are the two parks most under assault. Green campaigners were generally surprised and very pleased with the news, although wary as to the fine detail and as to what other companies might do.

"It's a very good step, a bold step to take, and we would welcome it," said Dave Bent, senior minerals planner for the Peak District National Park.

"The interesting thing is, what's going to happen with the other companies?"